Important: In order to avoid misdiagnosis, perform HVAC Air Delivery System Check before you begin the vacuum diagnosis procedure.

1. Inspect the vacuum supply to vacuum/electric solenoid (purple and black vacuum hoses) while engine is running:

•	Vacuum should be approximately 60 kPa (18 psi) with the engine running.

•	Vacuum should remain at approximately 60 kPa (18 psi) when the engine is turned OFF.

2. Test each vacuum actuator by disconnecting the vacuum hose and applying vacuum directly to the actuator. Repair or replace as necessary.
3. Reconnect all vacuum and electrical connections. Run the engine and cycle through the operating modes of the heater-A/C control while observing the valve actuators.

•	Inspect for vacuum to the mode valve actuators by noting the mode valve actuator position. When vacuum is applied, the actuator will retract, refer to the Air Delivery Vacuum Distribution table.

•	If a vacuum actuator retracts when it should not, replace the HVAC control assembly. Refer to Control Assembly Replacement .

•	If a vacuum actuator does not retract when it should, inspect for vacuum leaks, collapsed vacuum hoses or binding valves. If these components are OK, replace the vacuum/electric solenoid.